Occurrence of Pesticides in Streams of the Cheney Reservoir Watershed, South-Central Kansas, 1997-99

Abstract

Kansas is important to about 300,000 people in the Wichita area that rely on the reservoir as a source of drinking water. About 52 percent of the watershed is used for the production of grain crops, which generally rely on the use of pesticides for efficient production. Some pesticides subsequently may be transported in runoff water to Cheney Reservoir. The potential exposure to pesticides is of concern. The purpose of this fact sheet is to describe the occurrence of pesticides in streams within the Cheney Reservoir watershed. Pesticide concentrations are compared with Federal water-quality criteria for pesticides such that public and private organizations can evaluate the potential risks from pesticide exposure.

Significant finding of water-quality studies and implications for Cheney Reservoir watershed, south-central Kansas, 1996-2001

“…Fifteen herbicides, one herbicide metabolite, and six insecticides were detected in streamflow samples from the Cheney Reservoir watershed. The herbicides alachlor, atrazine, and metolachlor were detected in 61, 99, and 96 percent, respectively, of all streamflow samples (Milligan and Pope, 2000).…”

“…An MCL has not been established for metolachlor. The variability in median concentrations of alachlor, atrazine, and metolachlor among the six surfacewater-quality sampling sites probably is the result of variations in pesticide usage, amount of precipitation and runoff, topography, agricultural practices, and soil characteristics such as particle-size composition, porosity, and erodibility among the subwatershed areas represented by the sampling sites (Milligan and Pope, 2000).…”

“…The implication of long-term exposure to small concentrations of pesticides in most streamflow samples for the population that relies on Cheney Reservoir as a drinking-water source is not of great concern on the basis of current 2001water-quality criteria. However, the long-term effects of small concentrations of pesticides on aquatic life are not well known and may be an issue within the watershed (Milligan and Pope, 2000).…”